page_title: White-tailed eagle
section_title: Mammals and other prey
hierarchical_section_title: White-tailed eagle / Dietary biology / Mammals and other prey
caption_attribution_description: Eesti: Täiskasvanud merikotkas Hiiumaa rabas.
context_page_description: The white-tailed eagle is a very large species of sea eagle widely distributed across temperate Eurasia. As are all eagles, it is a member of the family Accipitridae which includes other diurnal raptors such as hawks, kites, and harriers. One of up to eleven members in the genus Haliaeetus, which are commonly called sea eagles, it is also referred to as the white-tailed sea-eagle. Sometimes, it is known as the ern or erne, gray sea eagle and Eurasian sea eagle
  While found across a very wide range, today breeding as far west as Greenland and Iceland across to as far east in Hokkaido, Japan, they are often scarce and very spottily distributed as a nesting species, mainly due to human activities. These have included habitat alterations and destruction of wetlands, about a hundred years of systematic persecution by humans followed by inadvertent poisonings and epidemics of nesting failures due to various manmade chemical pesticides and organic compounds, which have threatened eagles since roughly the 1950s and continue to be a potential concern. Due to this, the white-tailed eagle was considered endangered or extinct in several countries.
context_section_description: Mammals are usually a quite secondary component of the diet. Although usually better represented than other non-fish and bird prey, their regional importance is variable. In known dietary studies, the mammalian contribution can vary from 0.49% to 41% of prey by number. When mammals are most significant to the diet, it usually due to local white-tailed eagles preying on rabbits and hares with some regularity. In some studies from Scotland, the European rabbit (Oryctolagus cuniculus) and mountain hare (Lepus timidus) were found to contribute as much as nearly 25% of the diet. A similar contribution of European hares (Lepus europaeus) was found in the diet from Austria, where hares were the leading prey species making up 24.35% of 349 prey items (with mammals making up 34.67% of the overall diet). In studies from Germany, European hares were taken fairly often but were numerically secondary prey. Given that these rabbits and hares have average mature weights from 1.8 kg (4.0 lb) in rabbits to 3.8 and 4.2 kg (8.4 and 9.3 lb) in European and Arctic hares (Lepus arcticus), they can make a hearty contribution to the prey biomass when available (although certainly juveniles are attacked as much if not more so than adult rabbits and hares). Other large mammalian prey can include foxes, with 3.2 kg (7.1 lb) Arctic foxes (Vulpes lagopus) being the 6th most regular prey species in Greenland and about a dozen 5.77 kg (12.7 lb) red foxes (Vulpes vulpes) recorded as taken or scavenged in Norway (predaceous attacks on adult red foxes have been reportedly witnessed). In both the offshore islands of Norway, where Arctic hare can be important prey, and Greenland, where the Arctic fox are prey, large numbers of both are taken when their pelage remains white but snow melts prematurely. A white-tailed eagle was once observed to kill and feed on a live adult golden jackal (Canis auereus) that was trapped in a furbearer's trap. White-tailed eagles are known to prey on seal pups but most are likely sickly and perhaps both adult and pup seals are most likely to be eaten as carrion. Four Baikal seal (Pusa sibirica) pups were taken in Lake Baikal. They are considered a predator even for live grey seal (Halichoerus grypus) pups that weigh 11.75 kg (25.9 lb) at birth. In one instance, a white-tailed eagle reportedly tried to attack an adult harbor seal (Phoca vitulina) but was immediately dragged into the water and soon surfaced dying with a broken wing. Similarly, in one anecdote, an eagle drowned while apparently attacking an adult harbor porpoise (Phocoena phocoena). At least 7 species of mustelid have been recorded in the white-tailed eagle's diet, from the smallest weasel to, rarely, even adult European otters (Lutra lutra). Another mustelid, the American mink (Neovison vison) was introduced as a furbearer to Finland but then became an invasive pest, as a fast-breeding killer that threatens many native species. In turn, Finnish white-tailed eagles have become the main natural control and may inhibit the mink from breeding via heavy predation. Conversely, the white-tailed eagle have not been known to prey on the critically endangered, native European mink (Mustela lutreola) (perhaps due to its shier habits) which the American mink are known to have been outcompeting in some areas (but the European has mainly declined due to massive overhunting by humans as a furbearer). Kits of larger mammals such as Eurasian (Castor fiber) and North American beavers (Castor canadensis) (introduced) and of European badger (Meles meles) have been found as prey.
  The most widely reported mammalian prey known (albeit usually as a supplemental prey species) in the non-native muskrat (Ondatra zibethicus), which averages about 1.1 kg (2.4 lb), and may be taken from “muskrat farms” or feral wetland populations. While largely a supplemental prey item, a respectable number of 137 were recorded in the diet from Finland. Also, a study on the Ili delta in Kazakhstan has shown up to 30-43% of prey remains at eyries to consist of muskrat in spring and fall but only 14% in summe
caption: White-tailed eagle adult on the island of Hiiumaa in Estonia.
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